Hello everyone! Yesterday morning I started my car and a few seconds later, the engine started running strangely. It vibrates, runs hard. I stopped the engine and started it again: everything is fine! So I go for a ride around the block and at the first stop... it starts again (except this time the check engine light comes on). I look for the error code and it's P0301. My prestone level remains unchanged. I reset the error code before making the following replacements: I changed the ignition coils and spark plugs. Unfortunately, the engine still vibrates when starting (sometimes). In traffic... it can start to sputter randomly again. If I press the gas pedal even a little, it returns to normal. After about 90 kilometers (about 56 miles), as soon as I stop and start again, when accelerating it gives a knock (seems to come from the transmission?!?) around 30kph (18mph) everything returns to normal. The check engine still hasn't turned back on despite the things I've noticed since replacing the coil packs and spark plugs. I don't really know what to look at anymore... since it seems like there are two problems at the same time: 1- the engine seems to start vibrating as soon as it goes from EV mode to combustion mode. 2- When I start accelerating, it gives a knock up to about 30kph (18mph) If anyone has any ideas... what to check... (Prestone level is good, no prestone found in the oil). Thanks in advance!
Code P0301 indicates problems in the first cylinder. Have you inspected the spark plugs, checked the coils? It may also be a problem with a broken head gasket, when the coolant enters the cylinder drop by drop. You can inspect with an endoscope on a cold engine for drops on the cylinder walls.
Before replacing them all… I switched the first one and put on the cylinder 2 and the coil no.2 at the first cyclinder (the problem remain without any check engine)
So… its now confirmed… Head Gasket… I started my car this morning so I could clear the driveway. When I started it, the strange sound came back at the beginning and stopped like 30 sec later. And 5 minutes after starting my car, I looked at the prestone level. It went down below the "low" line. Which has never been the case with my car. Mystery now solved
Not much of a mystery, thousands have been there done that with gen3. The real issue now is a $2k head gasket gamble or a $3500 rebuilt engine sure thing?
Honestly… I think it will go to the scrapyard or I’ll buy a used motor from Japan… Not sure about that at this moment. The car is rough and the body too…
More rationally... Normally, the prestone would have mixed with the oil and would have increased the quantity (the excess prestone should increase the quantity of oil?!) Because currently my oil level has not moved. Could it be that it is the EGR that causes this noise? I am trying to understand because normally an HG will cause the presence of prestone in the oil and at least increase the level abnormally... in the link, the sound of my vehicle when started: https://share.icloud.com/photos/003L6hP9ysy6qdd490tE-KoBQ
In these Prius gen3s with hg problems it is normally a slow leak manifesting as drops between a cylinder coolant passage and the cylinder. Most of the time that leak does not continue into the cylinder long enough to accumulate and drain past the rings to the sump. It burns off and goes out the exhaust. An advanced case can accumulate and hydrolock the piston but the strong mg1 torque will simply bend the connecting rod, occasionally exploding it through the block. Shudder video “Hey Walt… they want to wait and see if it gets worse…” Best HG Diagnostic Car Care Nut HG Borescope at 660 sec
[ Not with 3rd gen Prius. The EGR causes clogs, head gasket fails (typically starting on cylinder one, and the failure is typically coolant leaking into the combustion chamber(s).
I'm at the very first stages of coolant use and twice it had a misfire during light acceleration. I know it's the head gasket failing at 167k miles on my '10. I'm having Gasket Masters replace it for ~$2000. Much cheaper than a dealer or independent shop. With buyin a used engine, you have a Used Engine. Won't you feel silly when that head gasket goes bad? There is an American made FelPro head gasket that hopefully is better quality than the OEM.
